This study concerns measurements of uveal capillary perfusion and of aqueous humor bulk flow using methods of anterior chamber clearances of xenon133 and I125 human serum albumin. Its purpose is to elucidate pathophysiologic mechanisms of disease with emphasis on changes in dynamic functions measured by the clearance method. In addition the uptake and turnover of isotopic zinc by uvea has also been studied in an effort to measure trace metal metabolism of that tissue.